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Date:   Wed, 17 Feb 2021 10:26:18 +0100
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     Pavel Machek <pavel@ucw.cz>
Cc:     linux-kernel@vger.kernel.org, stable@vger.kernel.org,
        Vincenzo Frascino <vincenzo.frascino@arm.com>,
        Andrey Konovalov <andreyknvl@google.com>,
        Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Alexander Potapenko <glider@google.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Leon Romanovsky <leonro@mellanox.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        "Paul E . McKenney" <paulmck@kernel.org>,
        Naresh Kamboju <naresh.kamboju@linaro.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Sasha Levin <sashal@kernel.org>
Subject: Re: [PATCH 5.10 043/104] kasan: add explicit preconditions to
 kasan_report()
Message-ID: <YCzhOtZd3ldvEzvk@kroah.com>
References: <20210215152719.459796636@linuxfoundation.org>
 <20210215152720.867409732@linuxfoundation.org>
 <20210216115029.GA25795@amd>
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On Tue, Feb 16, 2021 at 12:50:29PM +0100, Pavel Machek wrote:
> Hi!
> 
> > From: Vincenzo Frascino <vincenzo.frascino@arm.com>
> > 
> > [ Upstream commit 49c6631d3b4f61a7b5bb0453a885a12bfa06ffd8 ]
> > 
> > Patch series "kasan: Fix metadata detection for KASAN_HW_TAGS", v5.
> > 
> > With the introduction of KASAN_HW_TAGS, kasan_report() currently assumes
> > that every location in memory has valid metadata associated.  This is
> > due to the fact that addr_has_metadata() returns always true.
> > 
> > As a consequence of this, an invalid address (e.g.  NULL pointer
> > address) passed to kasan_report() when KASAN_HW_TAGS is enabled, leads
> > to a kernel panic.
> ...
> > This patch (of 2):
> > 
> > With the introduction of KASAN_HW_TAGS, kasan_report() accesses the
> > metadata only when addr_has_metadata() succeeds.
> > 
> > Add a comment to make sure that the preconditions to the function are
> > explicitly clarified.
> 
> As the other patch from the series is not applied, I don't believe we
> need this in stable. Changelog does not make any sense with just
> comment change cherry-picked...

Good point, now dropped, the AUTOBOT triggered off of the changelog text
which is nice and scary :)

greg k-h